Paper feeding device for copying machines



1968 MINORU UMAHASHl 3,

PAPER FEEDING DEVICE FOR COPYING MACHINES Filed Aug. 19, 1966 ATTORNEYSUnited States Patent 3,414,255 PAPER FEEDING DEVICE FOR COPYING MACHINESMinoru Umahashi, Tokyo, Japan, assignor to Kabushiki Kaisha Ricoh,Tokyo, Japan, a corporation of Japan Filed Aug. 19, 1966, Ser. No.573,628 Claims priority, application Japan, Aug. 21, 1965, 40/50,927 9Claims. (Cl. 270-58) ABSTRACT OF THE DISCLOSURE In a copying machine,feed means for sensitized paper adapted to adjust the speed of advanceof said paper in relation to the original sheet to insure continuedalignment of said sheets as they progress through the machine.

This invention relates to a copying machine of the type in which anoriginal document is automatically superimposed on a sheet of sensitizedpaper and the combined sheets are then fed into an exposure device. Moreparticularly, the invention relates to a copying machine adapted toreceive the original document, automatically remove a sheet ofsensitized paper from a storage stack, superimposed the originaldocument on the sensitized sheet in a predetermined position relativethereto, and advance the combined document and sensitized sheet into anexposure device at a pre-selected advance rate. The invention relates tothe feed mechanism for the type of machine described above, and moreparticularly to the sensing element which initiates the advance of thesensitized sheet.

It is an object of the invention to avoid variations in the relativepositions of the original document and the sensitive sheet as they enterthe exposure device, where such variations might otherwise occur as theresult of variations of the advance rate from one machine cycle to thenext.

Further objects of the invention will be apparent from the followingdescription, in which:

FIG. 1 shows a schematic side view of a feed device embodying theinvention, and

FIG. 2 and FIG. 3 are graphs illustrating relationships between theposition of an original document within the feed device and the time ofactivation of the sensitized paper advancing mechanism.

Referring to FIG. 1, an insertion mouth 1 is shown adapted to receivethe leading edge of an original document (the original hereafter). Anoriginal so inserted is received on conveyor belt 2 which is driven inthe direction of the arrow by the rollers 3 and 4. A guide plate 5 isprovided above, and parallel with, the conveyor belt 2. An original feedroller 6 and a feed-out roller 7 cooperate with conveyor belt 2 androllers 3 and 4 to advance the original through the machine.

Beneath the structure just described there is located a device foradvancing a sheet of sensitized paper, comprising an endless conveyorbelt 8 driven by rollers 9 and 10 in the direction of the arrow. Rollers11 and 12 are driven by contact with conveyor belt 8 in the direction ofthe arrows. A guide plate extends between these rollers above the beltsurface. A stack of sensitized paper 13 is held within the machine,supported on a perpendicularly movable sensitized paper support platform14. A sensitized paper feeding device 15 of a type well known in the artcomprises a rotatable feed-out roller 16, mounted on a supporting arm17. The feeding device is activated by an electric signal from amicroswitch 20 which is located above the conveyor belt 2 and has asensing wire 20a projecting into the path of the original through a holein guide plate 5. When the leading edge of the original strikes thesensing wire, the microswitch is closed and a signal transmitted.Activation of feeding device 15 results in rotation of the feed-outroller 16 which drives the top sheet of sensitized paper 13 into thebight between roller 11 and conveyor belt 8.

With both conveyors in operation the sensitized paper and the originalare fed along converging paths into the big-ht between the guide rollers18 and 19, where the original is superimposed on the sensitized paper.Rotation of the guide rollers as shown by the arrows feeds the combinedoriginal and sheet of sensitized paper into an exposure device P fromwhich they may pass to an automatic separating device S. Here thesensitized paper is separated from the original and is fed to adeveloping section D where it is developed and discharged from themachine. The original may also be discharged or, as an alternative,returned for a second cycle by mechanism not shown to the insertionmouth 1, as indicated by a dashed line.

It is desirable in machines of the type described to provide for meansto vary the rate of advance of the sensitized paper and the superimposedoriginal into the exposure device P. Such variations may be required inorder to match the exposure time to the characteristics of the originalor of the sensitized paper, for example. Since both the original and thesensitized paper must advance between guide rollers 18 and 19, insynchronism, one way to achieve variations in the advance rate is tovary equally the rate of roller 16, conveyor belts 2 and 8, and thevarious other guide rollers. It has been found, however, that anadjustment producing equal variations in the rates of these componentswill not always result in a desired superimposition of the original onthe sensitized paper at the new rate of advance. In other words, if, forexample, a desired superimposition is achieved when the advance rate hasa certain value, and that value is doubled by doubling the speed of therollers and conveyor belts, it will usually be found that the desiredsuperimposition no longer takes place. Instead, the original will reachthe guide rollers 18 and 19 too far in advance of the sheet ofsensitized paper.

The cause of the misalinement mentioned above is as follows: There is afixed delay between the time that the leading edge of the originalactivates the microswitch 20 and the time that the uppermost sheet ofsensitized paper begins to move from stack 13 at the selected advancerate. The delay is the result of the inability of components such asfeeding device 15 and roller 16, in-

stantaneously to reach operating position and a steady speed. In amachine in which the guide rollers and conveyor belts always operate ata fixed speed, this fixed delay can be compensated for by properlypositioning the microswitch 20. For example, suppose it is desired thatthe leading edges of both the original and the sensitized paper coincideas they pass through guide rolls 18 and 19. With both conveyor beltstravelling at the desired fixed speed, it is only necessary to positionmicroswitch 20 so that the time required for the leading edge of theoriginal to travel from the sensing wire 20a to the bight of guide rolls18 and 19 equals the sum of the delay time of feeding device 15 and thetime required for the leading edge of the sensitive paper to move fromstack 13 to the bight of these rolls.

If, however, the speed of the conveyor belts is to be made variable,there is no single position at which the microswitch 20 can be placedwhich will result in proper superimposition of the original on thesensitive paper at all speeds. This may be shown by examining theoperation of the machine at various speeds. Referring to FIG. 2, let Lrepresent the distance which the original travels after the microswitch20 is activated by its leading edge; let t denote the time after themicroswitch 20 is activated; let t be the delay time lapse between theinstant when the microswitch 20 is activated and the instant when thesheet of sensitized paper begins moving at the selected advance rate;and let v v and v respectively, represent the lowest, an intermediate,and the highest velocities at which the original and the sensitizedpaper are to be transported. If the microswitch sensing wire 20a islocated at a distance L such that the leading edges of both the originaland the sensitized paper coincide upon entering the bight of guide rolls18 and 19, when the speed of the belts is v then L v t -t-L where L isthe distance which the leading edge of the sensitized paper must travelto reach guide rolls 18 and 19. If L and L remain fixed in accordancewith the expression just given, but the speed of the belts and rollersis increased to v then the original will reach guide rolls 18 and 19before the sensitized paper, and the leading edge of the original willbe a distance D ahead of the leading edge of the sensitized paper, whereD =(v v )t It can be shown that if the speed of the belts and rolls isreduced to v under the same conditions, then the sensitized paper willreach the guide rolls 18 and 19 first, the leading edge thereofpreceding the leading edge of the original by an amount D, where D =(v-v )t The undesirable overlaps D and D may be eliminated by means of amovable mount for microswitch 20. As shown, this comprises a rack 22movable toward and away from guide rolls 18 and 19 and a pinion 21having a fixed axis and meshed with the rack. The microswitch is mountedon the rack and moves therewith. If the distance L from the microswitchsensing Wire a is set so that the edges coincide when the speed equals v(i.e., L =v t +L then the microswitch Will be in the position shown insolid lines in FIG. 1. If the belt and roller speed is increased to vthen the microswitch is moved by rack 22 away from guide rolls 18 and 19to the position 20' (shown in dashed lines), so that the distance fromthe microswitch sensing element 20a to guide rolls 18 and 19 is equal tothe expression If the speed v is employed, the rack moves themicroswitch closer to the guide rollers 18 and 19 so that the distancebetween them is equal to the expression The adjustments of themicroswitch position described may be made by linking pinion 21 to thecontrols which set the speed of the belts, so that a manual adjustmentof the belt speed control automatically adjusts the microswitch. Suchadjustments will cancel out the undesirable mismatching otherwise causedby variations in the feed rate. For example, pinion 21 may be splined torotatable shaft bearing an exposure dial (not shown) and connected toany one of various well known speed control devices (also not shown) inorder to regulate the output speed of such control device. A suitablespeed control might be a cone drive. Turning pinion 21 in such adirection as to move the microswitch 20 away from guide rollers 18 and19 would increase the output speed of the cone drive.

Referring to FIG. 3, it can be seen that if a desired overlap (or nooverlap if that is desired) occurs when advance rate v is employed, thenthe same overlap may be had if advance rate v is employed if themicroswitch is moved away from guide rollers 18 and 19 by an amount (v v)t,,. A line with slope equal to v when plotted with distance along thevertical axis and time along the horizontal axis strikes the verticalaxis at a given point, which has been made the origin in FIG. 3. If thepoint on this line (the line being indicated by L:v t) at t isascertained, and a second line (indicated as L=v t) with slope v isdrawn through said point, it will strike the vertical axis at a pointwhich is a distance (v v )t above the origin. Moving the microswitchaway from guide rollers 18 and 19 by this distance will compensate forthe speed change from v to v and will maintain the same overlap atadvance rate v as at v If a line having slope v is drawn through thepoint on line L=v t it will strike the vertical axis at a point abovethe point where the line L=v t strikes said axis. The distance betweensaid points of intersection with the vertical axis is (v v )z and if themicroswitch is advanced this amount toward the guide rollers .18 and 19when the advance rate is decreased from v to v the desired overlap willbe maintained.

It will be realized that in the event that it is desired to feed theoriginal and the sensitized paper into guide rolls 18 and 19 with theirleading edges out of register by a fixed amount which remainsindependent of the rate of advance, this can also be accomplished by asuitable choice of the dimensions L and L Such an out-of-registeradjustment may be desirable in order to allow automatic separator S topull the sheets apart after exposure in exposure device P. Once thedesired out-of-register overlap has been established for feed velocity,v for example, -further adjustments of the position of microswitch 20 bythe rack and pinion in response to velocity changes (as to v forexample) will maintain the desired overlap. Thus the arrangement shownis equally applicable to a machine in which the leading edge of thesensitized paper precedes (or follows) that of the document through theexposure device by a fixed amount. Subsequent speed adjustments will notvary the desired overlap.

It will be recognized that structural variations may be employed topractice the invention disclosed. For example, a cam-and-follower may besubstituted for the rack and pinions as a means of moving microswitch20, the cam being mounted on the speed control shaft. Alternatively,instead of microswitch 20, a movable photoelectric cell may be employedto sense the position of the leading edge of the original and initiatefeeding of the sensitized paper, Finally, instead of employing a single,movable microswitch a plurality of fixed microswitches located atvarying distances from the guide rollers 18 and 19 may be employed. Insuch a structure the belt speed control is coupled with a multipositionswitch which connects the feed device to the particular microswitchwhich is properly distant from the guide rollers for the particularspeed selected. The microswitch 20 for speed v would be at a positionindicated in solid lines in FIG. 1, that for speed v at position 20 andthat for speed v at position 20". The multiposition switch may be arotary one mounted on a speed control shaft.

In view of the possibility of using a plurality of fixed microswitchesas just described, the term elfective position of the sensing means isused herein to designate the position of that sensing means whichresponds to the presence of the leading edge of the original. The phrasevarying the effective position of the sensing means" is used to refernot only to the step of moving a single microswitch where a singlemicroswitch is used, but also to the step of disconnecting the secondsensitized paper feeding device from one microswitch and connecting itto a second microswitch placed at a different distance from guide rolls18 and 19, when a plurality of microswitches are used.

The following is claimed:

1. In a feeding device having first means for advancing during a feedingcycle a first piece of sheet material having a leading edge at aselected rate of advance along a first path; sensing means for sensingthe presence of the leading edge of the first piece of sheet material ata measuring point along the first path when said first piece of sheetmaterial is in the first path and for generating a signal in response tosaid presence at said measuring point; second means for advancing asecond piece of sheet material having a leading edge at the selectedrate of advance along a second path in response to the signal generatedby the sensing means, the operation of said second means beingcharacterized by a substantially constant delay period between thegeneration of the signal by the sensing means and the starting of theadvance of the second piece of sheet material at the selected rate ofadvance; and speed control means for changing the selected rate ofadvance between successive feeding cycles of the feeding device; theimprovement comprising position selection means for varying theeffective position of the sensing means and thereby varying the positionof the measuring point along the first path and connecting means linkingthe speed control means and the position selection means for causing theposition selection means to vary the effective position of the sensingmeans and thus to move the measuring point along the first path in thedirection of travel of the first piece of sheet material when the speedcontrol means is operated to decrease the rate of advance of said firstpiece of sheet material and for causing the position selection means tomove the fixed point along the first path in a direction opposite to thedirection of travel of the first piece of sheet material when the speedcontrols means is operated to increase the rate of advance of said firstpiece of sheet material.

2. The device of claim 1 wherein the position selection means comprisesmeans for moving the effective position of the sensing means in adirection opposite to the direction of movement of the first piece ofsheet material when the advance rate of said first piece of sheetmaterial is increased, said movement of the effective position of thesensing means being equal to the product of the substan tially constantdelay period and the difference between the new advance rate and the oldadvance rate.

3. An improvement in a copying machine, said copying machine havingmeans for feeding an original at a desired advance rate along a firstpath, means for changing the advance rate from one cycle of the machineto the next, removal means for removing a sensitized sheet of paper froma storage container and feeding it at the advance rate along a secondpath converging with the first path, said removal means being activatedby a signal and said removal means being characterized by asubstantially constant delay period from the time that the signal isreceived to the time that the sensitized sheet of paper begins travelingalong the second path at the desired advance rate, said improvementcomprising a sensing means for generating the signal when a selectedportion of the original reaches a measuring point in the first path andconnecting means for cooperating with the means for changing the advancerate and with the sensing means to move the effective position of thesensing means, and thus of the measuring point, in a direction oppositeto the direction of advance of the original when the rate of advance isincreased and in the same direction as the original when the rate ofadvance is decreased.

4. A copying machine comprising a first conveyor belt adapted to carryan original having a leading edge at a selected rate of advance in anadvancing direction; a sensing device in the path of an original beingcarried on the first conveyor belt and adapted to sense the leading edgeof the original as said leading edge reaches a measuring point, saidsensing device being adapted to originate a signal when it senses theleading edge; a storage device adapted to hold a plurality of sheets ofsensitized paper; a feeding device connected to the sensing device andadapted, upon receipt of a signal from the sensing device, to feed asheet of sensitized paper from the storage device to a second conveyorbelt; a second conveyor belt adapted to receive a sheet of sensitizedpaper from the feeding device and to carry said sheet at the selectedrate of advance; a speed control connected to the conveyor belts andadapted to change the rate of advance from one machine cycle to thenext; and a position selector coupled both to the speed control and tothe sensing device and adapted to change the effective position of thesensing device and thus the measuring point in accordance with changesin the rate of advance.

5. The device of claim 4 wherein the feeding device is characterized bya substantially constant delay period between the time when the signalis received and the time when the feeding device feeds a sheet ofsensitized paper to the second conveyor belt and wherein when the rateof advance is increased, the position selector changes the position ofthe measuring point in a direction opposite to the advancing directionby an amount equal to the product of the delay period and the differencebetween the old rate of advance and the new rate of advance.

6. The device of claim 5 where the position selector comprises a rack onwhich the sensing device is mounted, said rack being movable to and froin the direction of travel of the original, and a pinion meshed with therack and connected to the speed control for rotation in response tothose adjustments of the speed control which vary the rate of advance,said pinion, when rotated, effecting motion of the rack.

7. The device of claim 5 wherein the position selector comprises a camfollower on which the sensing device is mounted and a cam in drivingrelation to the cam follower, said cam being connected to the speedcontrol for rotation in response to adjustments of the speed controlwhich vary the rate of advance.

8. The device of claim 5 wherein the sensing device comprises aplurality of sensing elements, each of which is adapted to sense theleading edge of the original at a different position during its advanceand to generate a signal when it senses said leading edge, and in whichthe sensing device further comprises a multiposition switch movable intoa plurality of positions, in each one of which positions a differencesensing element is connected to the feed device and thereby is adaptedto transmit its signal thereto, and in which the position selectorcomprises a coupling between the speed control and the multi-positionswitch adapted to change the position of said switch in accordance withchanges in the rate of advance.

9. A copying machine comprising a first conveyor belt operable at aselected advance rate and adapted to transport an original having aleading edge along a first path; a second conveyor belt operable at theselected advance rate and adapted to transport a sheet of sensitizedpaper having a leading edge along a second path converging with thefirst path; speed control for varying the selected rate of advancebetween cycles of the machine; rotatable member associated with thespeed control and rotatable in response to those changes in the settingof the speed control which vary the selected rate of advance; a pinionmounted on and rotatable with the rotatable member; a rack meshed withsaid pinion and movable in response to rotation of said pinion to andfro along the direction of the first conveyor belt, said rack beingmovable in a direction contrary to the direction of motion of theoriginal in the first path when the rotatable member rotates in responseto changes in the setting of the speed control which increase the rateof advance; a microswitch movable with the rack and having a sensingWire positioned in the first path and adapted to emit a signal when thesensing wire contacts the leading edge of an original moving in thefirst path, a storage device adapted to support a stack of sheets ofsensitized paper; and a feeding device connected to the microswitch andactivated by a signal from the microswitch, said feeding device when soactivated being adapted to feed a sheet of sensitized paper from thestorage device to the second conveyor 10 belt.

References Cited UNITED STATES PATENTS 2,883,929 4/1959 Eichenbaurn eta1. 27058X 3,017,816 1/1962 Stuckens 27058 X 3,143,947 8/1964 Limberger27058 X EUGENE R. CAPOZIO, Primary Examiner.

P. WILLIAMS, Assistant Examiner.

